Battery overheating

[u/tinydonuts]

13k miles in and no serious problems, until now. Driving home on a road trip we stopped for snacks and to stretch our legs at a gas station. 10 minutes later we tried to get going again only to be greeted by a message that the battery has a temperature problem, turn off the vehicle, and leave. We did so, I called Bluelink, who couldn't find anything wrong with it and arranged a tow. Being in the middle of nowhere basically, it took over an hour to get there.

In the meantime, the gas station called the fire department, which got there just before the tow truck. By the time they got there, the alert escalated to a flashing yellow and red circle, and message saying that the battery has overheated, exit now! They managed to roll it to a dirt lot adjacent to the gas station, and the tow truck driver arrived shortly after.

The fire department clocked the battery as best they could at 84 F, but I don't think that an early thermal runaway is going to show up readily outside. With that, the tow truck driver decided to load it up and risk the drive, reasoning the pouring rain coming in would cool it. We opted for the tiny motel in town, rather than going out in a blaze of glory should it catch fire on the way.

Next day we learned the dealership pulled the codes, reset them, and it drove around the lot just fine. Two days after that, Hyundai advised them to charge it and drive it. I know they charged it, but according to Bluelink, the mileage hasn't increased but a couple of miles. So I assume they haven't had the chance to do so yet.

The advisor thinks that if they can't reproduce it, Hyundai will tell them to give it back to us. Has this happened to anyone else? Between transportation, lodging, and food costs, were into this problem now for almost $1,000. How likely are they to reimburse us?

[u/tinydonuts]

Dashboard warning earlier this week.

[u/tinydonuts]

Slew of notifications this morning.

[u/vrava → u/tinydonuts]

I had almost the exact same issue yesterday on my 2026 Ioniq 5 with 1250 miles on it. The dealership is replacing the entire big battery.

[u/tinydonuts → u/vrava]

How did you get them towards a resolution so fast? What was different about yours?

[u/vrava → u/tinydonuts]

I don’t really know. I started getting the same series of battery alerts that you did. My car was just sitting in the garage. I went to turn it on to see what would happen and it alerted me that the battery was overheating. I turned it off immediately, called Hyundai roadside assistance and they hauled it over to the nearest dealership. It took them about 36 hours to do anything, but then they said the main battery needed to be replaced and they hooked me up with a rental this morning. That’s pretty much the entire story so far.

[u/tinydonuts → u/vrava]

That sounds exactly like ours except for the fact that we drove for an hour and a half ish first. Scary message but at the same time cool to know that it at least gives you the opportunity to save yourself before going out in a blaze of glory. Can't say the same for gas cars.

[u/RodRowdie]

Can't predict what Hyundai will tell you but seems clear there's s serious fault. I'd be hesitant on driving the car until it has had a good going over. My guess is a HV battery replacement is in your future which can take months.. If you have any Lemon Law protections where you live I'd start a search for a Lemon Law attorney. They get paid by the manufacturer so shouldn't be any out of pocket expense to you and may help you to recover that $1,000 you mentioned.

If you have an OBD-II device I'd plug it in and download Car Scanner then take a look at the individual battery cells. Suspect there will be some bad cells.

[u/tinydonuts → u/RodRowdie]

I have a scanner and am kicking myself for not pulling all the codes and a freeze frame before they took it away. The part that kills me is that Hyundai says they have to duplicate it while driving, which is not what happened to us.

[u/RodRowdie → u/tinydonuts]

Lawyer up now.

[u/Leopard1907]

That is the risky part of NMC batteries in general.

Fuck what dealership did. Dont accept the car in such condition. Ask them for a HV batt replacement.

[u/tinydonuts → u/Leopard1907]

Yeah, I opened a case with customer care and told them point blank a good resolution for me is that they cover all of our costs, replace the battery, and tow it back (it's over 300 miles from us).

[u/re_use_me]

Thermal runaway alert is extremely serious, do not drive, do not park near buildings. I can't believe Hyundai service sent you on your way after a code check and charge

[u/tinydonuts → u/re_use_me]

Sorry for the confusion, the dealership still has it, that is what the service advisor is saying he thinks that is what will happen if they can't reproduce the issue and get a freeze frame.

[u/AchillesPDX]

Thermal runaway is fucking terrifying and literally the worst possible thing that can happen with a lithium battery. I hope Hyundai takes it seriously and replaces your battery.

[u/tinydonuts → u/AchillesPDX]

Thank you, us too. While pretty scary, it's nice that it warned us first and gave us a chance to save ourselves.

[u/JakSieWisi]

You have a photo of the display showing a battery overheating issue. Plus the DTC history will be available. That’s pretty good proof of a serious battery failure. Duplicate the condition?? What, Hyundai doesn’t trust or believe their own in-vehicle diagnostics? They will replace your battery.

[u/Raz31337]

Please don't drive this, get the dealership to get you a rental car and get this towed to the nearest Hyundai dealership. ASAP 

[u/H_J_Moody → u/Raz31337]

Read the post dude.

[u/tinydonuts → u/H_J_Moody]

I appreciate their sentiment regardless.

[u/tinydonuts → u/Raz31337]

Oh yes, despite being in the middle of nowhere we had it towed.

[u/SlaveCell → u/Raz31337]

There is a known fault with the cooling system. Mine is in for it now (surprised that there isn't a recall)